This invention relates to splints or braces and more particularly to splints designed to support the lower leg, ankle and foot to prevent foot-drop and other similar conditions that can result from prolonged immobility or bed rest.
A person who must be immobilized or confined to bed for a significant period of time, such as a person who has suffered a stroke or similar disability, may develop a variety of conditions resulting from the weakening of the leg and foot muscles and global tendons, such as foot-drop, knee flexion and inversion or eversion of the foot. Foot-drop results from the weakening or atrophy of the muscles in the foot and lower leg from lack of use. The upper leg muscles and Achilles tendon contract from lack of use, bending the knee joint (called knee flexion) to pull the knee upward and the foot downward. The foot also drops downwardly from its normal position, which is substantially perpendicular to the leg, to a position in which the foot is extended at an obtuse angle to the leg. In addition, when the knee is pulled up, it often will also rotate inward or outward, causing the entire lower leg and foot to rotate in the same direction. Similarly, immobilization can also result in the contraction of the upper or lower tendons in the foot, causing the foot to curve inward or outward (called foot inversion or eversion).
Unless a person can maintain his or her foot in a functional position, i.e. directed at a 90.degree. angle outward from the leg, it is very difficult to stand or walk. Consequently, prolonged bed rest or immobility, without taking the necessary preventive steps, may result in a person's losing the ability to stand or walk. Although such conditions subsequently can be corrected, it is much easier to prevent the conditions in the first place. In addition, when a patient's leg or foot rotates as a result of immobility or prolonged bed rest, bed sores commonly result. As the patient's leg or foot rotates and is pressed downward onto the bed, such sores develop through pressure necrosis at the point of contact with the bed's surface. Moreover, the contracting leg and foot muscles and tendons tend to reduce or cut off circulation to the extremities by increasing the amount of pressure, further contributing to the development of bed sores.
Numerous prior art devices have been designed to prevent or correct foot-drop and other similar conditions, such as the devices shown in U.S. Pat. Nos. 3,976,059; 2,874,991; 3,345,654; 3,527,209; 3,713,437; 3,916,886; 4,289,122; and 4,554,912. Such devices, however, suffer from several design drawbacks, including: lack of stability for standing or walking; rounded surfaces that promote rotation or rocking of the foot when the patient is in a prone position; lack of sufficient flexibility to permit the patient's foot to move against and bend the splint as a form of active exercise; lack of adequate attachment and support means; lack of any provision for preventing the patient's foot or leg from turning to one side or the other while the patient is in a prone position; a design that may injure the upper calf muscles; and protrusions or surfaces along the interior and exterior of the splint which themselves can irritate and thus cause sores on a patient's foot and/or leg.
For example, U.S. Pat. No. 3,976,059 shows a splint with a rounded heel which provides an unstable configuration for standing or walking. U.S. Pat. No. 3,916,886 discloses a splint which employs a strap adjacent the top and flanges along the periphery for attachment to a patient's foot, an arrangement which may not adequately support and secure the lower leg and foot of the patient in the splint.